Conductive bonding tape with low passive intermodulation

Abstract

The conductive adhesive tape includes a conductive self-supporting first layer that is conductive in each of three mutually orthogonal directions and includes conductive opposing first and second major surfaces, a conductive second layer having at least 60% by weight nickel coated on the first major surface of the self-supporting first layer, the conductive second layer having an exposed major surface facing opposite the first major surface of the self-supporting first layer and exposing at least a portion of the nickel in the second layer, and a conductive adhesive third layer bonded to the second major surface of the self-supporting first layer opposite the second layer, the adhesive third layer being conductive in at least one of the three mutually orthogonal directions and including a plurality of conductive elements dispersed within an insulating material, at least a portion of the conductive elements being in physical contact with the self-supporting first layer.

Description

Summary of the Invention

[0001] In some embodiments herein, a conductive adhesive tape is provided, the conductive adhesive tape comprising a conductive self-supporting first layer, a conductive second layer coated on a first major surface of the self-supporting first layer, and a conductive adhesive third layer bonded to a second major surface of the self-supporting first layer opposite the second layer. The conductive self-supporting first layer is conductive in each of three mutually orthogonal directions and has conductive opposite first and second major surfaces. The conductive self-supporting first layer has an average thickness greater than about 4 microns. The conductive second layer comprises at least 60% nickel by weight, the layer having an average thickness greater than about 0.03 microns. The conductive second layer has an exposed major surface facing the opposite side of the first major surface of the self-supporting first layer and exposing at least a portion of the nickel in the second layer. The adhesive third layer is conductive in at least one of the three mutually orthogonal directions and comprises a plurality of conductive elements dispersed in a substantially electrically insulating material. At least a portion of the conductive elements are in physical contact with the second major surface of the self-supporting first layer.

[0002] In some embodiments herein, a conductive adhesive tape is provided, the conductive adhesive tape comprising a conductive self-supporting nickel first layer, conductive at least through a thickness of the adhesive tape, and having at least 80% nickel by weight, and a conductive adhesive second layer. The conductive self-supporting nickel first layer is conductive in each of three mutually orthogonal directions, includes conductive opposite first and second major surfaces, and has an average thickness of greater than about 4 microns. The conductive adhesive second layer is bonded to the second major surface of the self-supporting first layer. The adhesive second layer is conductive in at least one of the three mutually orthogonal directions, and includes a plurality of conductive elements dispersed in a substantially electrically insulating material. At least some of the conductive elements are in physical contact with the second major surface of the self-supporting first layer. [Brief description of the drawings]

[0003] [Figure 1A]FIG. 2 is a side view of a conductive bonding tape according to one embodiment herein. [Figure 1B] FIG. 2 is a side view of one embodiment of a conductive element in a conductive bonding tape, according to one embodiment herein. [Figure 1C] FIG. 2 is a side view of one embodiment of conductive elements in a conductive bonding tape arranged in an alternating orientation, according to one embodiment herein. [Diagram 2] FIG. 1 is a side view of an electronic system featuring a conductive bonding tape according to an embodiment herein. [Figure 3A] 1A-1C show cross-sectional views of a conductive particle and a conductive fiber, respectively, according to one embodiment herein. [Figure 3B] 1A-1C show cross-sectional views of a conductive particle and a conductive fiber, respectively, according to one embodiment herein. [Figure 4] FIG. 2 is a side view of a conductive bonding tape according to an alternative embodiment herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0004] In the following description, reference is made to the accompanying drawings, which form a part hereof, and in which various embodiments are shown by way of illustration. The drawings are not necessarily to scale. It is to be understood that other embodiments are contemplated and may be made without departing from the scope or spirit of the present specification. Accordingly, the following detailed description is not to be construed in a limiting sense.

[0005] Passive intermodulation (PIM) is the generation of interference signals in electrical systems that can result from nonlinearities in the mechanical components of the system. This occurs when certain structural elements in the system (e.g., interconnects between components, corroded components, etc.) act like diodes and generate undesirable interference signals, including harmonics or intermodulation generation. Sometimes, tapes and / or foils may be added to the system to provide grounding or EMI shielding to components in the system; these added layers sometimes add interfaces between components that can contribute to the amount of PIM generated and can degrade the performance of the system.

[0006] Low PIM surface interfaces on foil and cloth tapes are important for radio frequency (RF) electromagnetic noise reduction and improved signal-to-noise ratio (SNR) performance in modern RF devices such as cell phones. A common but expensive solution to provide a low PIM interface for grounding in RF or similar devices is to add a gold coating to the ground or connection interface. However, gold is very expensive and adds significant cost to the system. Therefore, a tape with an improved backing (i.e., reducing PIM interference but without the excessive cost) is desirable.

[0007] According to some embodiments herein, a new foil / cloth tape solution is provided that can be applied to high PIM surfaces and can improve the resulting PIM performance over similar tapes with gold backing or solutions that use a more expensive sputtered gold interface on the surface of the end device. In some embodiments herein, the conductive bonding tape includes a conductive self-supporting first layer, a conductive second layer coated on a first major surface of the self-supporting first layer, and a conductive adhesive third layer bonded to a second major surface of the self-supporting first layer opposite the second layer.

[0008] In some embodiments, the conductive self-supporting first layer may be conductive in each of three mutually orthogonal directions (e.g., the x-axis, y-axis, and z-axis of the layer) and have conductive opposite first and second major surfaces. In some embodiments, the first layer may be substantially equally conductive in each of the three mutually orthogonal directions. In some embodiments, the conductive self-supporting first layer may have an average thickness of greater than about 4 microns, or about 6 microns, or about 8 microns, or about 10 microns, or about 20 microns, or about 50 microns, or about 75 microns, or about 100 microns, or about 125 microns, or about 150 microns, or about 175 microns, or about 200 microns. In some embodiments, the first layer may be a copper foil layer.

[0009] In some embodiments, the conductive second layer may comprise at least 60%, or at least 70%, or at least 80%, or at least 90%, or at least 95%, or at least 98%, or at least 99%, or at least 99.5% nickel by weight, and may have an average thickness of greater than about 0.03 microns, or about 0.04 microns, or about 0.05 microns, or about 0.1 microns, or about 0.25 microns, or about 0.5 microns, or about 1 micron, or about 2 microns, or about 3 microns, or about 4 microns, or about 5 microns. In some embodiments, the second layer may comprise nickel or a nickel alloy.

[0010] In some embodiments, when the second layer includes a nickel alloy, the nickel alloy may include one or more of a nickel vanadium alloy (NiV), a nickel chromium alloy (NiCr), a nickel tin alloy (SnNi), a nickel phosphorus alloy (NiP), a nickel titanium alloy (NiTi), and a nickel niobium alloy (NiNb). In embodiments including a nickel vanadium alloy (NiV), the weight percentage of nickel may range from about 90% to about 96%, and the weight percentage of vanadium may range from about 4% to 10%. In embodiments including a nickel chromium alloy (NiCr), the weight percentage of nickel may range from about 70% to about 90%, and the weight percentage of chromium may range from about 10% to 30%. In embodiments including a nickel tin alloy (SnNi), the weight percentage of nickel may range from about 25% to about 45%, and the weight percentage of tin may range from about 55% to 75%. In embodiments including nickel phosphorus alloys (NiP), the weight percentage of nickel may range from about 80% to about 95% and the weight percentage of phosphorus may range from about 5% to 20%. In embodiments including nickel titanium alloys (NiTi), the weight percentage of nickel may range from about 50% to about 70% and the weight percentage of titanium may range from about 30% to 50%.

[0011] In some embodiments, the conductive second layer may have an exposed major surface facing away from the first major surface of the self-supporting first layer, exposing at least a portion of the nickel in the second layer. In some embodiments, the adhesive third layer may be conductive in at least one of three mutually orthogonal directions (e.g., the z-axis or thickness direction of the layer) and may include a plurality of conductive elements dispersed in a substantially electrically insulating material. In some embodiments, at least a portion of the conductive elements may be in physical contact with the second major surface of the self-supporting first layer. In some embodiments, the conductive elements in the adhesive third layer may include one or more of conductive particles and conductive fibers. In some embodiments, the conductive particles may include insulating particles coated with one or more conductive coatings. In some embodiments, the conductive fibers may include insulating fibers (34a) coated with one or more conductive coatings (34b, 34c).

[0012] In some embodiments, the conductive adhesive tape of claim 1 may further include a conductive fourth layer sandwiched between and bonded to the conductive adhesive third layer and the conductive adhesive fifth layer. In some embodiments, the adhesive fifth layer may be conductive in at least one of three mutually orthogonal directions (e.g., the z-axis or thickness direction of the layer). In some embodiments, the fifth layer may include a plurality of conductive elements dispersed within a substantially electrically insulating material. In some embodiments, at least some of the conductive elements of the fifth layer may be in physical contact with the fourth layer.

[0013] According to some aspects herein, the electronic system may include a substrate including one or more of stainless steel, aluminum, and titanium (or other conductive metal substrate or coating including indium tin oxide), the aforementioned bonding tape including a conductive fourth layer and a conductive adhesive fifth layer, and a conductive elastic component (e.g., a conductive spring clip) that is elastically pressed against and in physical contact with the exposed major surface of the second layer. In some embodiments, the conductive elastic component may include a gold coating or gold coated connection points, where the gold coating or connection points are in physical contact with the exposed major surface of the second layer.

[0014] According to some embodiments herein, the conductive bonding tape may be conductive at least through a thickness of the bonding tape and may include a conductive self-supporting nickel first layer having at least 80% by weight, or at least 85% by weight, or at least 90% by weight, or at least 95% by weight, or at least 98% by weight, or at least 99% by weight, or at least 99.5% by weight nickel, and a conductive adhesive second layer.

[0015] In some embodiments, the conductive self-supporting nickel first layer may be conductive in each of three mutually orthogonal directions and may include conductive opposed first and second major surfaces. In some embodiments, the nickel first layer may have an average thickness greater than about 4 microns, or about 6 microns, or about 8 microns, or about 10 microns, or about 20 microns, or about 50 microns, or about 75 microns, or about 100 microns, or about 125 microns, or about 150 microns, or about 175 microns, or about 200 microns.

[0016] In some embodiments, the conductive adhesive second layer may be bonded to the second major surface of the self-supporting first layer. In some embodiments, the adhesive second layer is conductive in at least one of three mutually orthogonal directions and includes a plurality of conductive elements dispersed in a substantially electrically insulating material. In some embodiments, at least some of the conductive elements may be in physical contact with the second major surface of the self-supporting first layer.

[0017] In some embodiments, the conductive adhesive tape may further include a conductive third layer sandwiched between and bonded to the conductive adhesive second layer and the conductive adhesive fourth layer. In some embodiments, the adhesive fourth layer may be conductive in at least one of three mutually orthogonal directions. In some embodiments, the adhesive fourth layer may include a plurality of conductive elements dispersed within a substantially electrically insulating material. In some embodiments, at least some of the conductive elements of the fourth layer may be in physical contact with the third layer.

[0018] In some embodiments, the conductive adhesive tape may further include a conductive fifth layer coated on the first major surface opposite the second major surface of the first layer. In some embodiments, the fifth layer may include at least 20% by weight, or at least 30% by weight, or at least 40% by weight, or at least 50% by weight, or at least 60% by weight, or at least 70% by weight, or at least 80% by weight nickel. In some embodiments, the fifth layer may have an average thickness of greater than about 0.03 microns, or about 0.04 microns, or about 0.05 microns, or about 0.1 microns, or about 0.25 microns, or about 0.5 microns, or about 1 micron, or about 2 microns, or about 3 microns, or about 4 microns, or about 5 microns.

[0019] In some embodiments, the conductive fifth layer may comprise a nickel alloy including one or more of nickel vanadium alloy (NiV), nickel chromium alloy (NiCr), nickel tin alloy (SnNi), nickel phosphorus alloy (NiP), nickel titanium alloy (NiTi), and nickel niobium alloy (NiNb). In embodiments including nickel vanadium alloy (NiV), the weight percentage of nickel may range from about 90% to about 96%, and the weight percentage of vanadium may range from about 4% to 10%. In embodiments including nickel chromium alloy (NiCr), the weight percentage of nickel may range from about 70% to about 90%, and the weight percentage of chromium may range from about 10% to 30%. In embodiments including nickel tin alloy (SnNi), the weight percentage of nickel may range from about 25% to about 45%, and the weight percentage of tin may range from about 55% to 75%. In embodiments including nickel phosphorus alloys (NiP), the weight percentage of nickel may range from about 80% to about 95% and the weight percentage of phosphorus may range from about 5% to 20%. In embodiments including nickel titanium alloys (NiTi), the weight percentage of nickel may range from about 50% to about 70% and the weight percentage of titanium may range from about 30% to 50%.

[0020] In some embodiments, the adhesive second layer may be more conductive in its thickness direction than in any orthogonal in-plane direction. In other embodiments, the adhesive second layer may be more conductive in its in-plane direction than in the thickness direction. That is, the conductive elements in the adhesive second layer may be configured such that the adhesive second layer is conductive in the thickness direction of the layer (e.g., the z-axis of the layer) or in the in-plane direction of the layer (e.g., the plane defined by the x-axis and y-axis of the layer). In some embodiments, the conductive elements in the adhesive second layer may include one or more of conductive particles and conductive fibers. In some embodiments, the conductive particles may include insulating particles coated with one or more conductive coatings. In some embodiments, the conductive fibers may include insulating fibers coated with one or more conductive coatings.

[0021] Referring now to the drawings, Figure 1A is a side view of one embodiment of a conductive adhesive tape according to the present disclosure. In some embodiments, the conductive adhesive tape 100 may include a conductive first layer 10. In some embodiments, the conductive first layer 10 may be a copper foil. In other embodiments, the conductive first layer 10 may be a nickel first layer comprising at least 80% nickel by weight. The conductive first layer 10 has a conductive first major surface 11 and an opposing conductive second major surface 12.

[0022] In some embodiments, the conductive second layer 20 may be coated on the first major surface 11 of the self-supporting first layer 10. In some embodiments, the second layer 20 may comprise at least 60%, or at least 70%, or at least 80%, or at least 90%, or at least 95%, or at least 98%, or at least 99%, or at least 99.5% nickel by weight. In some embodiments, the second layer may have an average thickness of greater than about 0.03 microns, or about 0.04 microns, or about 0.05 microns, or about 0.1 microns, or about 0.25 microns, or about 0.5 microns, or about 1 micron, or about 2 microns, or about 3 microns, or about 4 microns, or about 5 microns, and may have an exposed major surface 21 facing the opposite side of the first major surface 11 of the self-supporting first layer 10 and exposing at least a portion of the nickel in the second layer 20.

[0023] In some embodiments, the conductive adhesive tape 100 may further include a conductive adhesive third layer 30 bonded to the second major surface 12 of the first layer 10 opposite the second layer 20. In some embodiments, the conductive third layer 30 may include a plurality of conductive elements 31 dispersed within a substantially electrically insulating material 32. In some embodiments, at least some of the conductive elements 31 may be in physical contact with the second major surface 12 of the self-supporting first layer 10. In some embodiments, at least some of the conductive elements 31 may be arranged such that the third layer 30 is conductive at least in the z-axis (i.e., the z-axis shown in FIG. 1A, or in the thickness direction of the third layer 30). In some embodiments, such as the embodiment shown in FIG. 1A, the conductive elements 31 may include conductive particles. In other embodiments, such as the embodiment shown in FIG. 1B, the conductive elements 31 may include conductive fibers. In some embodiments, the conductive elements 31 may include both conductive particles and conductive fibers (see also FIGS. 3A and 3B).

[0024] In some embodiments, for example in the embodiment of FIG. 1C , at least some of the conductive elements 31 may be arranged such that the third layer 30 is conductive at least in the in-plane direction (i.e., the plane defined by the x-axis and y-axis shown in FIG. 1A ), but the conductivity through the thickness (i.e., the conductivity through the z-axis or thickness of the layer) may be reduced compared to the conductivity in the in-plane direction.

[0025] In some embodiments, the conductive adhesive tape 100 may further include a conductive fourth layer 40 sandwiched between and bonded to the conductive adhesive third layer 30 and the conductive adhesive fifth layer (50). In some embodiments, the adhesive fifth layer 50 may include a plurality of conductive elements 51 that are conductive in at least one of three mutually orthogonal directions (e.g., the z-axis) and dispersed in a substantially electrically insulating material 52. In some embodiments, at least some of the conductive elements 51 of the fifth layer 50 may be in physical contact with the fourth layer 40. In some embodiments, such as the embodiment shown in FIG. 1A, the conductive elements 51 may include conductive particles. In other embodiments, such as the embodiment shown in FIG. 1B, the conductive elements 51 may include conductive fibers. In some embodiments, the conductive elements 51 may include both conductive particles and conductive fibers (see also FIGS. 3A and 3B).

[0026] In some embodiments, for example, in the embodiment of FIG. 1C, at least some of the conductive elements 51 may be arranged such that the fifth layer 50 is conductive at least in the in-plane direction (i.e., the plane defined by the x-axis and y-axis shown in FIG. 1A), but the conductivity through the thickness (i.e., the conductivity through the z-axis or thickness of the layer) may be reduced compared to the conductivity in the in-plane direction.

[0027] As described elsewhere herein, the first layer 10 may be a copper foil layer and the second layer may include a nickel alloy. In some embodiments, the nickel alloy may include one or more of nickel vanadium alloy (NiV), nickel chromium alloy (NiCr), nickel tin alloy (SnNi), nickel phosphorus alloy (NiP), nickel titanium alloy (NiTi), and nickel niobium alloy (NiNb). In embodiments including nickel vanadium alloy (NiV), the weight percentage of nickel may range from about 90% to about 96%, and the weight percentage of vanadium may range from about 4% to 10%. In embodiments including nickel chromium alloy (NiCr), the weight percentage of nickel may range from about 70% to about 90%, and the weight percentage of chromium may range from about 10% to 30%. In embodiments including nickel-tin alloys (SnNi), the weight percentage of nickel may range from about 25% to about 45% and the weight percentage of tin may range from about 55% to 75%. In embodiments including nickel-phosphorus alloys (NiP), the weight percentage of nickel may range from about 80% to about 95% and the weight percentage of phosphorus may range from about 5% to 20%. In embodiments including nickel-titanium alloys (NiTi), the weight percentage of nickel may range from about 50% to about 70% and the weight percentage of titanium may range from about 30% to 50%.

[0028] Figure 2 is a side view of one embodiment of an electronic system 200 featuring the embodiment of the conductive adhesive tape 100 of Figure 1 A. Like numbered elements in the conductive adhesive tape 100 of Figure 1 A shown in Figure 2 have like functional descriptions unless otherwise specified, and descriptions of these features may not be repeated in the description of Figure 2.

[0029] 1 disposed on the substrate 80 with an adhesive fifth layer 50 bonded to the substrate, and a conductive elastic component 70 (e.g., a spring clip) that is resiliently pressed into contact with the exposed major surface 21 of the second layer 20. In some embodiments, the conductive elastic component 70 can include a gold coating or contact 75 such that the gold coating 75 is in physical contact with the exposed major surface 21 of the second layer 20. In some embodiments, the substrate 80 can include one or more of stainless steel, aluminum, and titanium.

[0030] In some embodiments, the conductive elastic component 70 can be any suitable conductive contact that contacts the exposed major surface 21 of the second layer 20 of the conductive adhesive tape 100, including, but not limited to, conductive foam, spring clips, screws, springs, pins, conductive fingers, conductive fabrics, and conductive metal substrates.

[0031] In the previous figures, embodiments of the conductive third layer 30 and the conductive adhesive fifth layer 50 have been shown to include a plurality of conductive elements 31 and 51, respectively. Figures 3A and 3B provide cross-sectional views of embodiments of conductive particles 33 and conductive fibers 34, respectively.

[0032] FIG. 3A illustrates conductive particles 33. In some embodiments, the conductive particles 33 may include insulating particles 33a coated with one or more conductive coatings 33b and 33c. Similarly, FIG. 3B illustrates conductive fibers 34. In some embodiments, the conductive fibers 34 may include insulating fibers 34a coated with one or more conductive coatings 34b and 34c. As shown in FIGS. 1A and 2, at least some of the conductive elements 31, 51 (the conductive particles 33 in FIG. 3A and / or the conductive fibers 34 in FIG. 3B) may be in physical contact with the second major surface 12 of the first layer 10 and the fourth layer 40, respectively, to create a conductive path away from the corresponding layer.

[0033] In some embodiments, the self-supporting layer of the conductive adhesive tape may be nickel-based, rather than copper foil-based. Figure 4 is a side view of an alternative embodiment of a conductive adhesive tape 100'. In such an embodiment, the conductive adhesive tape 100' may include a conductive self-supporting nickel first layer 10' and a conductive adhesive second layer 30'.

[0034] In some embodiments, the nickel first layer 10' may be at least 80% by weight, or at least 85% by weight, or at least 90% by weight, or at least 95% by weight, or at least 98% by weight, or at least 99% by weight, or at least 99.5% by weight nickel. In some embodiments, the conductive self-supporting nickel first layer 10' may be conductive in each of three mutually orthogonal directions (e.g., the x-axis, y-axis, and z-axis as defined in FIG. 4) and may include a conductive first major surface 11' and an opposing second major surface 12'. In some embodiments, the nickel first layer 10' may have an average thickness of greater than about 4 microns, or about 6 microns, or about 8 microns, or about 10 microns, or about 20 microns, or about 50 microns, or about 75 microns, or about 100 microns, or about 125 microns, or about 150 microns, or about 175 microns, or about 200 microns.

[0035] In some embodiments, the conductive adhesive second layer 30' may be bonded to the second major surface 12' of the self-supporting first layer 10'. In some embodiments, the adhesive second layer 30' may be conductive in at least one of three mutually orthogonal directions (e.g., the z-axis or an in-plane direction defined by the x-axis and y-axis). In some embodiments, the adhesive second layer 30' may include a plurality of conductive elements 31' dispersed within a substantially electrically insulating material 32'. In some embodiments, at least some of the conductive elements 31' may be in physical contact with the second major surface 12' of the self-supporting first layer 10'.

[0036] In some embodiments, the conductive adhesive tape may further include a conductive third layer 40' sandwiched between and bonded to the conductive adhesive second layer 30' and the conductive adhesive fourth layer 50'. In some embodiments, the adhesive fourth layer 50' may be conductive in at least one of three mutually orthogonal directions (e.g., the z-axis or an in-plane direction defined by the x-axis and y-axis). In some embodiments, the adhesive fourth layer 50' may include a plurality of conductive elements 51' dispersed within a substantially electrically insulating material 52'. In some embodiments, at least some of the conductive elements 51' of the fourth layer 50' may be in physical contact with the third layer 40'.

[0037] In some embodiments, the conductive elements 31' in the adhesive second layer 30' and / or the conductive elements 51' in the adhesive fourth layer 50' may include one or more of conductive particles and conductive fibers. In some embodiments, the conductive particles may include insulating particles coated with one or more conductive coatings. In some embodiments, the conductive fibers may include insulating fibers coated with one or more conductive coatings. For further details of the conductive particles 33 and the conductive fibers 34, see Figures 3A and 3B.

[0038] In some embodiments, the conductive bonding tape may further include a conductive fifth layer 60' coated on the first major surface 11' (opposite the second major surface 12') of the first layer 10'. In such embodiments, the fifth layer 60' may include at least 20% by weight, or at least 30% by weight, or at least 40% by weight, or at least 50% by weight, or at least 60% by weight, or at least 70% by weight, or at least 80% by weight nickel. In some embodiments, the fifth layer 60' may have an average thickness of greater than about 0.03 microns, or about 0.04 microns, or about 0.05 microns, or about 0.1 microns, or about 0.25 microns, or about 0.5 microns, or about 1 micron, or about 2 microns, or about 3 microns, or about 4 microns, or about 5 microns.

[0039] In some embodiments, the conductive fifth layer 60' may comprise a nickel alloy including one or more of a nickel vanadium alloy (NiV), a nickel chromium alloy (NiCr), a nickel tin alloy (SnNi), a nickel phosphorus alloy (NiP), a nickel titanium alloy (NiTi), and a nickel niobium alloy (NiNb). In embodiments including a nickel vanadium alloy (NiV), the weight percentage of nickel may range from about 90% to about 96%, and the weight percentage of vanadium may range from about 4% to 10%. In embodiments including a nickel chromium alloy (NiCr), the weight percentage of nickel may range from about 70% to about 90%, and the weight percentage of chromium may range from about 10% to 30%. In embodiments including a nickel tin alloy (SnNi), the weight percentage of nickel may range from about 25% to about 45%, and the weight percentage of tin may range from about 55% to 75%. In embodiments including nickel phosphorus alloys (NiP), the weight percentage of nickel may range from about 80% to about 95% and the weight percentage of phosphorus may range from about 5% to 20%. In embodiments including nickel titanium alloys (NiTi), the weight percentage of nickel may range from about 50% to about 70% and the weight percentage of titanium may range from about 30% to 50%. EXAMPLES

[0040] Preparation and testing of three reference substrates (Reference A-1, Reference A-2 and Reference B described below) and four example substrates (Example A, Example B, Example C-1 and Example C-2) constructed using the methods described herein have been completed. Results and test methods are described below.

[0041] Reference A-1 and Reference A-2: Direct metal pin grounding to high PIM substrate DC resistance, harmonics and passive intermodulation (PIM) interference were measured on two different substrate types (stainless steel and aluminum) with direct metal pin ground (no coating) and are shown in Table 1. For DC resistance, harmonics and PIM measurements, lower numbers (more negative numbers for PIM and harmonics) indicate improved performance over higher numbers. DC resistance, PIM and harmonics were measured using industry standard DC resistance meters, signal generators, spectrum analyzers and duplexers as needed to configure the specific DC resistance, PIM or harmonics test of the test printed circuit board and specimen under test.

[0042] Test method: Metal pin ground. Joint Size: Not applicable. Joint conditions: Gap spacing. Signal generator: -13.45dBm 869-894 Amplifier: 33.7dBm 33.7dBm Span: 100Hz RBW (resolution bandwidth): 10Hz VBW (Video Bandwidth): 50Hz SWP (sweep time): 5 seconds [Table 1]

[0043] Reference B: Metal pin ground on sputtered gold (Au) DC resistance, harmonics and passive intermodulation (PIM) interference were measured for metal pin grounds on stainless steel substrates with sputtered gold coating and are presented in Table 2. For DC resistance, harmonics and PIM measurements, lower numbers (more negative numbers for PIM and harmonics) indicate improved performance over higher numbers. DC resistance, PIM and harmonics were measured using industry standard DC resistance meters, signal generators, spectrum analyzers and duplexers as needed to configure the specific DC resistance, PIM or harmonic tests of the test printed circuit board and specimen under test.

[0044] Test method: Metal pin ground. Joint size: 10mm x 3mm. Joint conditions: Gap spacing. Signal generator: -13.45dBm 869-894 Amplifier: 33.7dBm 33.7dBm Span: 100Hz RBW (resolution bandwidth): 10Hz VBW (Video Bandwidth): 50Hz SWP (sweep time): 5 seconds [Table 2]

[0045] Example A: Metal pin ground on low PIM grounding tape DC resistance, harmonics and passive intermodulation (PIM) interference were measured for metal pin grounds on aluminum substrates covered with low PIM grounding tape prepared as described below and are presented in Table 3. For DC resistance, harmonics and PIM measurements, lower numbers (more negative numbers for PIM and harmonics) indicate improved performance over higher numbers. DC resistance, PIM and harmonics were measured using industry standard DC resistance meters, signal generators, spectrum analyzers and duplexers as needed to configure the specific DC resistance, PIM or harmonic tests of the test printed circuit board and specimen under test.

[0046] Test method: Metal pin ground. Joint size: 10mm x 3mm. Joint conditions: Gap spacing. Signal generator: -13.45dBm 869-894 Amplifier: 33.7dBm 33.7dBm Span: 100Hz RBW (resolution bandwidth): 10Hz VBW (Video Bandwidth): 50Hz SWP (sweep time): 5 seconds

[0047] Preparation of CPSA: Conductive pressure sensitive adhesives (CPSA) can be made by any desired means that allows the CPSA to achieve a conductive path between the desired substrates. A common method of making CPSA is to blend conductive fillers (nickel, silver, metal coated particles, fibers, etc.) into a resin matrix, solvent coat them onto a release liner, and dry and / or cure. Alternative methods include hot melt coating, 100% solids coating and curing (UV or thermal initiated cure initiation), etc.

[0048] For example, note that a solution of conductive pressure sensitive adhesive (PSA) was prepared as follows: 1 kg of acrylic copolymer solution, 40% solids (available from Truss LTD, Gyeongsangbuk-do under the trade name TA-H3300), 10 g of epoxy crosslinker solution, 10% solids (available from Truss LTD, Gyeongsangbuk-do under the trade name THAR-020), 15 g of 30 μm nickel particles (available from SNC TECH Co. Kyounggi-do, Korea under the trade name SML-30) and 350 g of ethyl acetate were mixed together using conventional high shear mixing to form an adhesive precursor solution. The adhesive precursor solution was then coated onto the low release side of a dual coated silicone polyester liner by conventional notch bar coating method and dried by passing through a tunnel drying oven. The coated adhesive material with conductive particles was then laminated to one side of a 15 micron thick conductive polyester nonwoven substrate (available under the trade name PNW-5-PCN™ from Ajin Electron, Busan, Korea) by passing it between a pair of laminating rolls, and then the conductive nonwoven adhesive was wound up into a roll.

[0049] Metal Foil Backing and Final Product Preparation - Metal layers can be applied to metal substrates by a variety of conventional methods based on the type of metal being applied (methods can include sputtering, plating, evaporation, chemical vapor deposition, E-beam, etc.). Note, for example, that NiCr (80:20) was sputtered to a thickness of 10 nm onto 12 μm nickel-plated Cu foil.

[0050] Final product Example A was prepared by laminating a foil backing onto the CPSA. [Table 3]

[0051] Example B: Metal pin ground on low PIM ground tape DC resistance, harmonics and passive intermodulation (PIM) interference were measured for metal pin grounds on aluminum substrates covered with low PIM grounding tape prepared as described below and are presented in Table 4. For DC resistance, harmonics and PIM measurements, lower numbers (more negative numbers for PIM and harmonics) indicate improved performance over higher numbers. DC resistance, PIM and harmonics were measured using industry standard DC resistance meters, signal generators, spectrum analyzers and duplexers as needed to configure the specific DC resistance, PIM or harmonic tests of the test printed circuit board and specimen under test.

[0052] Test method: Metal pin ground. Joint size: 10mm x 3mm. Joint conditions: Gap spacing. Signal generator: -13.45dBm 869-894 Amplifier: 33.7dBm 33.7dBm Span: 100Hz RBW (resolution bandwidth): 10Hz VBW (Video Bandwidth): 50Hz SWP (sweep time): 5 seconds

[0053] Preparation of CPSA: Conductive pressure sensitive adhesives (CPSA) can be made by any desired means that allows the CPSA to achieve a conductive path between the desired substrates. A common method of making CPSA is to blend conductive fillers (nickel, silver, metal coated particles, fibers, etc.) into a resin matrix, solvent coat them onto a release liner, and dry and / or cure. Alternative methods include hot melt coating, 100% solids coating and curing (UV or thermal initiated cure initiation), etc.

[0054] For example, note that a solution of conductive pressure sensitive adhesive (PSA) was prepared as follows: 1 kg of acrylic copolymer solution, 40% solids (available from Truss LTD, Gyeongsangbuk-do under the trade name TA-H3300), 10 g of epoxy crosslinker solution, 10% solids (available from Truss LTD, Gyeongsangbuk-do under the trade name THAR-020), 15 g of 30 μm nickel particles (available from SNC TECH Co. Kyounggi-do, Korea under the trade name SML-30) and 350 g of ethyl acetate were mixed together using conventional high shear mixing to form an adhesive precursor solution. The adhesive precursor solution was then coated onto the low release side of a dual coated silicone polyester liner by conventional notch bar coating method and dried by passing through a tunnel drying oven. The coated adhesive material with conductive particles was then laminated to one side of a 15 micron thick conductive polyester nonwoven substrate (available under the trade name PNW-5-PCN™ from Ajin Electron, Busan, Korea) by passing it between a pair of laminating rolls, and then the conductive nonwoven adhesive was wound up into a roll.

[0055] Preparation of Metal Foil Backing and Final Product - The foil backing for this example was based on 10um annealed pure nickel foil (>99.5% nickel) prepared for this example. The foil is designated NIFLA-10 and is available from Fukuda Metal Foil & Powder Co. LTD 20 Nakatomi-cho, Nishinoyama, Yamashina-ku, Kyoto 607-8305, Japan).

[0056] Final product Example B was prepared by laminating a nickel foil backing onto the CPSA. [Table 4]

[0057] Examples C-1 and C-2: Metal pin grounding on low PIM grounding tape DC resistance, harmonics and passive intermodulation (PIM) interference were measured for metal pin grounds on low PIM grounding tape of two different substrate types (stainless steel and aluminum) prepared as described below and are presented in Table 5. For DC resistance, harmonics and PIM measurements, lower numbers (more negative numbers for PIM and harmonics) indicate improved performance over higher numbers. DC resistance, PIM and harmonics were measured using industry standard DC resistance meters, signal generators, spectrum analyzers and duplexers as needed to configure the specific DC resistance, PIM or harmonics test of the test printed circuit board and specimen under test.

[0058] Test method: Metal pin ground. Joint size: 10mm x 3mm. Joint conditions: Gap spacing. Signal generator: -13.45dBm 869-894 Amplifier: 33.7dBm 33.7dBm Span: 100Hz RBW (resolution bandwidth): 10Hz VBW (Video Bandwidth): 50Hz SWP (sweep time): 5 seconds

[0059] Preparation of CPSA: Conductive pressure sensitive adhesives (CPSA) can be made by any desired means that allows the CPSA to achieve a conductive path between the desired substrates. A common method of making CPSA is to blend conductive fillers (nickel, silver, metal coated particles, fibers, etc.) into a resin matrix, solvent coat them onto a release liner, and dry and / or cure. Alternative methods include hot melt coating, 100% solids coating and curing (UV or thermal initiated cure initiation), etc.

[0060] For example, note that a solution of conductive pressure sensitive adhesive (PSA) was prepared as follows: 1 kg of acrylic copolymer solution, 40% solids (available from Truss LTD, Gyeongsangbuk-do under the trade name TA-H3300), 10 g of epoxy crosslinker solution, 10% solids (available from Truss LTD, Gyeongsangbuk-do under the trade name THAR-020), 15 g of 10 μm nickel particles (available from Duksan Hi-Metal Co. Ulsan, Korea under the trade name PNS-10R), and 350 g of ethyl acetate were mixed together using conventional high shear mixing to form an adhesive precursor solution. The adhesive precursor solution was then coated onto the low release side of a dual coated silicone polyester liner by conventional notch bar coating method and dried by passing through a tunnel drying oven.

[0061] Preparation of Metal Foil Backing and Final Product - The foil backing for this example was based on 5um pure nickel foil (>99.5% nickel) and was prepared for this example. The foil is called NIFL-5 and is available from Fukuda Metal Foil & Powder Co.LTD 20 Nakatomi-cho, Nishinoyama, Yamashina-ku, Kyoto 607-8305, Japan.

[0062] Final product examples C1 and C2 were prepared by laminating a nickel foil backing onto a CPSA. [Table 5]

[0063] Based on the above examples, it can be seen that the tape design embodiments described herein enable improved DC resistance, harmonics, and passive intermodulation (PIM) over pin-to-stainless steel or pin-to-aluminum ground test designs. The novel tape design embodiments described herein also show improvements over a gold layer applied to a stainless steel surface with respect to PIM and harmonics while achieving sufficiently low DC resistance.

[0064] Terms such as "about" are understood by those of skill in the art in the context in which they are used and described herein. Where the use of "about" as applied to quantities describing feature sizes, amounts, and physical properties is not otherwise clear to those of skill in the art in the context in which it is used and described herein, "about" is understood to mean within 10 percent of the particular value. A quantity given as about a particular value may be exactly that particular value. For example, where the use of "about" as applied to quantities describing feature sizes, amounts, and physical properties is not otherwise clear to those of skill in the art in the context in which it is used and described herein, a quantity having a value of about 1 means that the quantity has a value between 0.9 and 1.1, and may also be 1.

[0065] Terms such as "substantially" are understood by those of skill in the art in the context in which they are used and described herein. If the use of "substantially equal" is not clear to those of skill in the art in the context in which they are used and described herein, "substantially equal" means approximately equal, with about as above. If the use of "substantially parallel" is not clear to those of skill in the art in the context in which they are used and described herein, "substantially parallel" means within 30 degrees of parallel. Directions or surfaces described as substantially parallel to one another may, in some embodiments, be within 20 degrees or within 10 degrees of parallel, or may be parallel or nominally parallel. If the use of "substantially aligned" is not clear to those of skill in the art in the context in which they are used and described herein, "substantially aligned" means aligned within 20% of the width of the objects being aligned. Objects described as substantially aligned may, in some embodiments, be aligned within 10% or within 5% of the width of the objects being aligned.

[0066] All references, patents, or patent applications referenced above are hereby incorporated by reference in their entirety. In the event of any inconsistency or contradiction between any portion of the incorporated reference and this application, the information in the prior description shall prevail.

[0067] Descriptions of elements in the drawings should be understood to apply equally to corresponding elements in other drawings unless otherwise indicated. Although specific embodiments have been illustrated and described herein, it will be understood by those skilled in the art that the specific embodiments shown and described may be substituted with various alternative and / or equivalent embodiments without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Accordingly, the present disclosure is intended to be limited only by the claims and the equivalents thereof.

Claims

1. an electrically conductive, self-supporting first layer that is electrically conductive in each of three mutually orthogonal directions, that includes electrically conductive opposite first and second major surfaces, and that has an average thickness greater than about 4 microns; a conductive second layer coated on the first major surface of the self-supporting first layer, the conductive second layer comprising at least 60% by weight nickel, the conductive second layer having an average thickness greater than about 0.03 microns and an exposed major surface facing opposite the first major surface of the self-supporting first layer, exposing at least a portion of the nickel in the second layer; an electrically conductive adhesive third layer bonded to the second major surface of the self-supporting first layer opposite the second layer, the electrically conductive adhesive third layer being electrically conductive in at least one of the three mutually orthogonal directions and including a plurality of electrically conductive elements dispersed in a substantially electrically insulating material, at least some of the electrically conductive elements being in physical contact with the second major surface of the self-supporting first layer; and 1. A conductive bonding tape comprising:

2. The conductive adhesive tape of claim 1 , wherein said first layer is substantially equally conductive in each of said three mutually orthogonal directions.

3. The conductive adhesive tape of claim 1 , wherein the first layer is a copper foil layer.

4. The conductive bonding tape of claim 1 , wherein the second layer comprises nickel or a nickel alloy.

5. 5. The conductive bonding tape of claim 4, wherein the second layer comprises a nickel alloy including one or more of a nickel vanadium alloy (NiV), a nickel chromium alloy (NiCr), a nickel tin alloy (SnNi), a nickel phosphorus alloy (NiP), a nickel titanium alloy (NiTi), and a nickel niobium alloy (NiNb).

6. 6. The conductive adhesive tape of claim 5, wherein for the nickel-vanadium alloy (NiV), the weight percentage of the nickel ranges from about 90% to about 96% and the weight percentage of the vanadium ranges from about 4% to 10%.

7. 6. The conductive bonding tape of claim 5, wherein for the nickel chromium alloy (NiCr), the weight percentage of the nickel ranges from about 70% to about 90% and the weight percentage of the chromium ranges from about 10% to 30%.

8. 6. The conductive bonding tape of claim 5, wherein for the nickel-tin alloy (SnNi), the weight percentage of the nickel ranges from about 25% to about 45% and the weight percentage of the tin ranges from about 55% to 75%.

9. 6. The conductive adhesive tape of claim 5, wherein for the nickel phosphorus alloy (NiP), the weight percentage of the nickel ranges from about 80% to about 95% and the weight percentage of the phosphorus ranges from about 5% to 20%.

10. 6. The conductive adhesive tape of claim 5, wherein for the nickel titanium alloy (NiTi), the weight percentage of the nickel ranges from about 50% to about 70% and the weight percentage of the titanium ranges from about 30% to 50%.

11. The conductive adhesive tape of claim 1 , wherein the adhesive third layer is more conductive through its thickness than in any orthogonal in-plane direction.

12. The conductive adhesive tape of claim 1 , wherein the third adhesive layer is more conductive in its in-plane direction than in its thickness direction.

13. The conductive adhesive tape of claim 1 , wherein the conductive elements in the third adhesive layer include one or more of conductive particles and conductive fibers.

14. 2. The conductive adhesive tape of claim 1, further comprising a conductive fourth layer sandwiched between and bonded to the third and fifth conductive adhesive layers, the fifth adhesive layer being conductive in at least one of the three mutually orthogonal directions and comprising a plurality of second conductive elements dispersed in a substantially electrically insulating material, and at least a portion of the conductive elements of the fifth layer physically contacting the fourth layer.

15. a substrate comprising one or more of stainless steel, aluminum, and titanium; The conductive adhesive tape according to claim 14, wherein a fifth layer of adhesive is disposed on the substrate in a state where the fifth layer is bonded to the substrate; a conductive elastic component resiliently pressed against and in physical contact with the exposed major surface of the second layer; an electronic system,

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